Question

An electric dipole is formed from ± 5.0 nC point charges spaced 3.0 mm apart. The dipole is centered at the origin, oriented along the y-axis. a)What is the electric field strength at point (x,y) = ( 10 mm ,0cm)? b) What is the electric field strength at point (x,y) = (0cm, 10 mm )?

Answer 1

a = 3*10^-3 / 2 = 1.5*10^-3 m

r = 10*10^-3 m

q = 5*10^-9 C

a)

electricfield due to dipole at any axial point is given by

E = - k q a/ ( r^3)

E = 9*10^9*3* 10^-3* 5*10^-9 / (10*10^-3)^3

E = - 135000 N/C

Note : you can neglect negative sign in order to have just magnitude only

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b)

electric field on an equitorial point

E = k 2 q a / ( r^3)

E = 9*10^9* 2* 5*10^-9* 3*10^-3 / (0.01^3)

E = 270000 N/C

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